The field of the invention is weatherproof caulking compositions, and particularly automobile undercoatings.
The state of the prior art may be ascertained by reference to German published application No. 1,279,264 of Karl-Heinz Mielke et al, German Pat. No. 915,483 of Frederick J. Wehmer et al, U.S. Pat. Nos. 3,192,176 and 3,304,277 of Karl-Heinz Mielke et al, U.S. Pat. No. 3,230,162 of Gilchrist, and the Kirk-Othmer "Encyclopedia of Chemical Technology", 2nd Ed., Vol. 1 (1963), pages 224-240 under the section entitled "Acids, Carboxylic", and Vol. 19 (1969), pages 85-134 under the section entitled "Styrene Plastics".
U.S. Pat. No. 3,192,176 discloses a mixture of diene copolymers in acrylonitrile copolymer, while U.S. Pat. No. 3,304,277 discloses a metal primer of an acrylonitrile copolymer and a trialkyl phosphate additive. The patent of Gilchrist discloses polycarboxylic acid resins having .alpha. ,.beta.-unsaturated carboxylic acids and butadiene-styrene latices. Gilchrist also discloses the addition of alkyd resins.
Vol. 1 of Kirk-Othmer discloses unsaturated monocarboxylic acids at page 231, Table 4, and unsaturated di- and tri-carboxylic acids in Table 5 at page 232.
Styrene, butadiene and maleic anhydride copolymers are disclosed in Vol. 19 at page 91 of Kirk-Othmer.
Numerous attempts have been made heretofore to employ aqueous plastic dispersions for the normal priming of metals, which is followed by an additional lacquering step. Such products, which are known, for example, from German published application No. 1,279,264 of Karl-Heinz Mielke et al cannot be employed, however, for the application of thick layers, since they are not thixotropic and thus slide off from vertical surfaces.
Furthermore, organosols and plastisols of polyvinyl chloride resins have also been employed as corrosion-protective coating compositions. Likewise conventional are sealing compounds of an asphaltic base which contain, in addition to rubber solutions, fillers, and fibers, also considerable amounts of organic solvents (German Pat. No. 915,483 of Frederick J. Wehmer et al). Such coating compositions are completely unsuitable for the purposes of the present invention, since they are not sufficiently stable, and contain considerable amounts of organic solvents. The flammability of the coating compositions is obvious, because of the organic solvents incorporated therein.